1) Field of the Invention
The present invention relates to a method of and apparatus for regenerating a used adsorbent for exhaust gas treatment.
2) Description of the Related Art
To remove substances such as impurities, odor substances, staining substances, and harmful substances from a gaseous phase or liquid phase, and to separate a gas from a liquid, activated charcoal has hitherto been used.
Recently, to produce higher-grade chemical products and deal with environmental issues, low pollution, hygienic control and health issues, it has been desired to develop high-quality filters and adsorbents in these fields. With this tendency, a porous structural body having excellent adsorption and desorption performance has been required.
As the porous structural body, conventional carbon materials, such as activated charcoal and activated carbon fiber, may be mentioned. When activated charcoal is used as the adsorbent to treat exhaust gas released from a boiler and so forth, the activity of the activated charcoal decreases because heavy metals such as mercury (Hg) and selenium (Se) are adsorbed thereto.
When the carbon material is not reused, it may be combusted. However, since mercury is vaporized and scattered during the combustion, a filter must be used to adsorb mercury again.
To regenerate an adsorbent such as activated charcoal, a method for heating it at high temperature in an inert gas has been suggested (see Japanese Patent Application Laid-Open No. 2000-167395).
However, this method has a problem: it requires large-scale heating equipment. In addition, an exhaust-gas treatment apparatus such as a boiler is large-scale equipment. Accordingly, recycling of a used adsorbent is important for reducing the cost in continuous operation and thus a simple treatment method has been strongly desired.
In the metals adsorbed by activated charcoal, valuable metals such as Zr and Pd are sometimes included in addition to harmful metals. It is desired that these valuable metals are recycled for effective utilization of resources.
Moreover, when a valuable-metal containing material is processed, a wiping waste cloth used during the processing may contain the valuable metal and an ion exchange resin and chelate resin used in the processing may adsorb the metal. Therefore, a method of efficiently recovering such a metal from the waste cloth and resins has been desired.